1. Field of the Invention
The present invention relates to a motor, and more particularly, to a motor applied to an electric power steering (EPS) system.
2. Discussion of Related Art
Generally, a hydraulic steering device using hydraulic pressure of a hydraulic pump and an electric steering device using a motor are applied as steering devices in vehicles.
The hydraulic steering device consumes energy at all times regardless of a rotation of a steering wheel since the hydraulic pump, which is a power source supplying auxiliary steering power, is operated by an engine, whereas in the electric steering device, if a steering torque is generated by rotation of a steering wheel, auxiliary steering power proportionate to a steering torque is supplied to the motor.
The electric steering device is configured to have the auxiliary steering power transferred to a rack bar if the steering torque generated by the rotation of the steering wheel is transferred to the rack bar via a rack-pinion mechanism portion and the auxiliary steering power is generated in a steering motor based on the generated steering torque. That is, the steering torque generated by the steering wheel and the auxiliary steering power generated in the steering motor are combined to enable the rack bar to be moved in the axial direction.
A three phase motor is employed in the case of the steering motor, and the three phase motor generally includes a rotor having a magnetic body and a stator including three types of coils (U/V/W phase wires) receiving different phases of power having a phase difference of 120°.
Meanwhile, if an electrical short circuit occurs among the coils to which different phases of power are applied, the motor may malfunction or be damaged, causing a great risk of accidents due to generation of erroneous auxiliary steering power while driving.